/* 初始化样式 */
*{
    margin: 0;
    padding: 0;
    /* 改变盒子尺寸计算方式 */
    box-sizing: border-box;
    
}
li{
list-style: none;
}
a{
    text-decoration: none;
    color: inherit;
    cursor: pointer;
}

input ,button{
    border: none;
/* 移除外边距 */
    outline: none;
    background-color: transparent;
}
button{
    cursor: pointer;
    background-color: transparent;
}

.fl{
    float: left;
}
.fr{
    float: right;
}
.clearfix::after{
    content: "";
    display: block;
    clear: both;
}
h3{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
}